Floating roof tanks are common in the petroleum and chemical processing industries to store volatile liquids. In floating roof tanks, the roof is generally adapted with pontoons so that the roof floats on the surface of the liquid. Seals are typically provided at the peripheral edges of the roof to seal the roof as it floats up and down with the liquid level, thereby preventing the escape of vapors from the tank.
In floating roof tanks, it is typically necessary to provide an opening to allow operators to extract samples of the liquid from the tank. However, using such openings to extract samples requires the operator to physically stand upon the roof of the tank. In many cases, this is somewhat dangerous, such as where the tank may emit toxic vapors. This is especially a problem when the liquid level in the tank is low so that the roof of the tank is well-below the top of the tank's side walls. In such cases, the roof and the tank's side walls form a semi-enclosed space wherein vapors are not readily dispersed in the wind.
Accordingly, there is a need for a floating roof tank which can be sampled without having to stand on the tank roof.